I've seen people take the hard cover that covers the top of the Rhodes (not the curved plastic cover, but the covered wood one that hinges on for when you move it) and cut it so that the keys are exposed when the top is on. Then take that piece you cut off and hinge it onto the part you cut it off of, so you can close it up when you move it. Hard to describe but hopefully simple to visualize. Then put some shielding on the inside of the cover and stack anything you want on top.
-R